The Section of Pediatric Hematology/Oncology at the University of Chicago is base at Wyler Children's Hospital and LaRabida Children's Hospital and Research Center, a combined 211-bed facility emphasizing subspecialty care and the major pediatric teaching and research center for the Division of Biological Sciences and the Pritzker School of Medicine. The Section is affiliated with, an has access to, the resources of the on-site University of Chicago Cancer Research Center, an NCI designated clinical cancer center, and the Howard Hughes Institute. Previously an affiliate of the University of Indiana, the program obtained full member status in CCG in 1989, assuming responsibility for five affiliate institutions. The number of patients entered on CCG studies by this network has increased from 44 in 1989 to 121 in 1991, reflecting an increased contribution particularly of patients entered on therapeutic and biology studies. Future contributions of this institution and its network to CCG will predominantly be in the scientific areas where its faculty currently have leadership responsibilities: studies of acute lymphoblastic leukemia (ALL) - particularly high risk ALL, ALL in infants, ALL in adolescents and young adults and testicular ALL-Hodgkin's Disease, bone and soft tissue sarcomas, brain tumors, marrow transplantation, supportive care and the biology and molecular cytogenetics of childhood cancer. Dr. Nachman will continue to chair CCG-1882, the high-risk ALL protocol which is expected to accrue over 1200 patients, the testicular leukemia task force, the proposed group-wide Hodgkin's Disease study and the proposed osteogenic sarcoma pilot study (CCG-7006). He is a vice-chair of the Bone Tumor Strategy Group, of which Dr. Michael Simon (vice-chair of Orthopedic Surgery) is also a member, and the Section will remain a major contributor in pilot studies of intensive chemotherapy for osteogenic sarcoma and advanced sarcomas. The Section will continue to play a major role in developing and piloting studies of intensive chemotherapy and autotransplantation for malignant brain tumors. Dr. Johnson (a vice-chair of the Marrow Transplantation Committee) will direct of the Section's CCG studies of allogeneic marrow transplantation aimed at defining the role of post-transplant immunotherapy in preventing relapse, the effectiveness of earlier transplantation in high risk leukemia, the impact of the source of hematopoietic stem cells on outcome, and the effectiveness of cytokines in accelerating hematopoietic recovery. Dr. Stephen Smith, newly appointed to the Biology Research Committee, and Dr. Michelle LeBeau (member of the steering committee of the Cytogenetics Committee) will play a leadership role in studies of the biology and cytogenetics of childhood cancer. This network's patient accrual to CCG studies is expected to increase from the newly appointed affiliate institutions as they develop their programs, as the proposed studies (described in detail in the body of the grant) open, an with the establishment of a developmental therapeutics program enabling recruitment of patients to CCG phase I studies.